Examples of analysis methods that use a gas chromatograph include isothermal analysis in which the temperature in the column is kept constant and programmed-temperature analysis in which the temperature in the column is increased at a constant rate of temperature increase. Even with respect to the same sample, retention index values measured by these analysis methods are different if the set temperatures or rates of temperature increase are different. For this reason, conventionally, in qualitative analysis of an unknown specimen, the retention index of the unknown specimen is measured under the same temperature conditions as those used in measurement of a known retention index, and a comparison is performed.
Thus, in order to enable comparison between retention indices without the necessity for setting the same temperature conditions, the applicant of the present invention proposes, as disclosed in Patent Document 1, a method for estimating a retention index of a specific sample that would be obtained by performing isothermal analysis at any desired temperature from a plurality of retention indices that have been measured with respect to that sample by performing isothermal analysis at different temperatures, and a method for estimating a retention index that would be obtained by performing programmed-temperature analysis with any desired rate of temperature increase and initial temperature from a plurality of retention indices that have been measured by performing isothermal analysis at different temperatures.
Incidentally, in actual gas chromatographic analysis, programmed-temperature analysis, which can provide measurement results within a shorter period of time than isothermal analysis, is often used. Accordingly, there is a demand for an approach that can effectively use data on retention indices that have been previously measured by programmed-temperature analysis and accumulated, rather than a method for estimating a retention index based on retention indices measured by isothermal analysis.
However, a method for estimating, from known retention indices measured by programmed-temperature analysis, a retention index that would be measured with another rate of temperature increase is currently not known.